The Junkers D.I (factory designation J 9) was a

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

fighter aircraft Fighter aircraft (early on also ''pursuit aircraft'') are military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air supremacy, air superiority of the battlespace. Domina ...

produced in

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

late in

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

, significant for becoming the first all-metal fighter to enter service. The

prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototype ...

, a private venture by Junkers named the J 7, first flew on 17 September 1917, going through nearly a half-dozen detail changes in its design during its tests.Grosz and Terry 1984, p.67. When it was demonstrated to the ''

Idflieg The Idflieg (''Inspektion der Fliegertruppen'' - "Inspectorate of Flying Troops") was the bureau of the German Empire that oversaw German military aviation prior to and during World War I. Founded in 1911, the Idflieg was part of the ''Fliegert ...

'' early the following year it proved impressive enough to result in an order for three additional aircraft for trials. The changes made by Junkers were significant enough for the firm to rename the next example the J 9, which was supplied to the ''Idflieg'' instead of the three J 7s ordered. Junkers D

During tests, the J 9 lacked the manoeuvrability necessary for a front-line fighter but was judged fit for a naval fighter and a batch of 12 was ordered. These were supplied to a naval unit by September 1918, which then moved to the Eastern Front after the Armistice.

Variants

;J 7 :company designation for early prototype variants, one built (three completed as J 9s). ;J 9 : company designation for late prototypes and production models ;J 9/II : company designation for lengthened fuselage version ;D.I : Idflieg designation

Surviving aircraft

One example survives and is on display in the

Musée de l'Air et de l'Espace The Musée de l'air et de l'espace (, ) is a French aerospace museum, located at the south-eastern edge of Paris–Le Bourget Airport, north of Paris, and in the Communes of France, commune of Le Bourget. It was inaugurated in 1919 after a propo ...

, at the

Paris–Le Bourget Airport Paris–Le Bourget Airport () is an airport located within portions of the communes of Le Bourget, Bonneuil-en-France, Dugny and Gonesse, north-northeast of Paris, France. Once Paris's principal airport, it is now used only for general a ...

, 11km north of

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

. Several copies have been built, including one on display at the Militärhistorisches Museum Flugplatz Berlin-Gatow.

Specifications

References

Citations

Bibliography

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External links

Fokker D.VII, Halberstadt CL.IV and Junkers D.I

Junkers D.I at Musée de l'Air et de l'Espace, Le Bourget
{{World War I Aircraft of the Central Powers 1910s German fighter aircraft D.I Single-engined tractor aircraft Aircraft first flown in 1917